1. Field of the Invention
The present invention relates generally to vapor compression refrigerating systems and modules which are used in such vapor compression refrigerating system. In particular, the present invention is directed towards vapor compression refrigerating systems and modules in which the module comprises a gas-liquid separator and a heat exchanger disposed within, e.g., surrounded by, the gas-liquid separator.
2. Description of Related Art
An exemplary, known vapor compression refrigerating system, such as the vapor compression refrigerating system described in Japanese Patent Publication No. JP-A-11-193967, uses a natural refrigerant, such as carbon dioxide, as a refrigerant. The known vapor compression refrigerating system includes an inside heat exchanger for exchanging heat between refrigerant at an exit side of a radiator and refrigerant at a suction side of a compressor, which increases an efficiency of the vapor compression refrigerating system.
One exemplary, known vapor compression refrigerating system is depicted in FIG. 11. The high-temperature and high-pressure refrigerant compressed by a compressor 201 is introduced into a radiator 202, and heat is exchanged between the refrigerant and an outside fluid. The refrigerant flows from radiator 202 to an inside heat exchanger 203, and then from inside heat exchanger 203 to a pressure-reducing mechanism 204 which reduces the pressure of the refrigerant. The pressure reduced refrigerant flows from pressure-reducing mechanism 204 to an evaporator 205, and then from evaporator 205 to a gas-liquid separator 206. The gas-liquid separator 206 then separates a gas portion of the refrigerant from a liquid portion of the refrigerant, stores the liquid portion of the refrigerant, and the gas portion of the refrigerant flows from gas-liquid separator 206 to inside heat exchanger 203. Heat then is exchanged between the refrigerant which flows from radiator 202 to inside heat exchanger 203 and the gas portion of the refrigerant which flows from gas-liquid separator 206 to inside heat exchanger 203. The gas portion of the refrigerant then flows from inside heat exchanger 203 to compressor 201.
In a vapor compression refrigerating system including such an inside heat exchanger, a pressure in the high-pressure side of the system may be elevated by decreasing a specific enthalpy of refrigerant at the exit side of the radiator, as compared with a refrigerating system which does not include an inside heat exchanger. Consequently, it may be possible to improve a coefficient of performance of the system, and to prevent a liquid compression of the compressor by providing a certain degree of superheating to the refrigerant which is sucked into the compressor.
When carbon dioxide is used as the refrigerant, although the refrigerant discharged from the compressor is cooled by the radiator, because the refrigerant at the outlet of the radiator may reach a supercritical condition without being liquefied when a temperature of an outside fluid, e.g., air, to be exchanged in heat with the refrigerant in the radiator exceeds a certain temperature, e.g., a temperature greater than the critical temperature of carbon dioxide, if the pressure of the refrigerant is reduced and the refrigerant is evaporated by an evaporator, the refrigeration ability of the refrigeration system may substantially decrease. Therefore, exchanging heat between the refrigerant at the exit side of the radiator and the refrigerant at the suction side of the compressor via the inside heat exchanger may increase or maintain the refrigeration ability of the refrigerating system, and also may reduce the pressure of the high-pressure side and improve the coefficient of performance of the refrigerating system.
Another known vapor compression refrigerating system is described in Japanese Patent Publication No. JP-A-2004-100974. In this known vapor compression refrigerating system, the number of refrigerant tubes and coupling portions thereof are reduced by integrally forming the inside heat exchanger around a refrigerant storing space of the gas-liquid separator, thereby reducing the number of parts used in the refrigerating system and the amount of space occupied by the refrigerating system.
Nevertheless, when the inside heat exchanger is provided as a single, separated piece of equipment, because refrigerant tubes and coupling portions therefor are required for the inside heat exchanger, it may be difficult to reduce the cost of the system. Further, when the inside heat exchanger is integrated with the gas-liquid separator around the gas-liquid separator, although the number of the refrigerant tubes and the coupling portions therefor is reduced, the configuration of the integrated equipment may become complicated, and it may be difficult to practically manufacture the integrated equipment. Moreover, oil in the gas-liquid separator may remain inside the inside heat exchanger integrated with the gas-liquid separator.